MICROBIAL DISEASES OF MAN AND ANIMALS. 593 



In man simple rubbing of virulent cultures into the skin is often suf- 

 ficient to produce a furuncle. 



Upon entering the tissue the cocci are strongly chemotactic and pus 

 inevitably results. With virulent cultures the leucocidal substance is 

 more or less strongly active. The organism may be limited to the first 

 abscess or by invasion of the blood stream multiple abscesses result. 

 In these cases, which are usually fatal, the organism will be found through- 

 out the body. 



Immunization can be secured by repeated injections of cocci dead 

 or alive in graduated doses. The sera possess slight bactericidal and 

 agglutinating properties, and a high degree of opsonic power. The 

 latter property is probably the most important. 



The sera of immunized animals is protective only when used slightly 

 before or along with the injection of the organisms and is consequently 

 of little practical value. Active immunization, however, is being exten- 

 sively practised particularly with the autogenous strains. Leucocyte 

 extracts have also been successfully though not so widely used. 



The prophylaxis of staphylococcic infections is the same as for other 

 pus-producing forms. 



Several other kinds of staphylococci have been found associated with 

 pathological conditions, the most important of which are M. pyogenes 

 var. albus, M. epidermidis albus (Welch), and M. pyogenes var. citreus. 

 The first seems to be slightly pathogenic, and rarely produces severe 

 infection. It is distinguished from the aureus by lack of pigment. 



The second variety appears to be an attenuated form of the other. 



The third variety is distinguished from aureus and albus only by the 

 development of a lemon-yellow pigment. 



STREPTOCOCCIC INFECTIONS.* 



General Septiccemia, Puerperal Septicaemia, Erysipelas, Etc. 

 Streptococcus pyogenes. 



Streptococcic infections are endemic among all races and under all 

 social conditions. In the days before antisepsis and our knowledge of 

 the transmission of infectious diseases, erysipelas and puerperal septicaemia 

 occurred in epidemics that were the scourges of surgical and lying-in 

 hospitals. 



* Prepared by Edward Fidlar. 

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